Method of and apparatus for producing electrical conductor wire

Abstract

A method of and an apparatus for producing an electrical conductor wire, especially a profiled heavy wire wherein the wire to be coated is guided subsequently through applying means, calibrating means and through a hardening chamber in which the individual layers of varnish are exposed to ultraviolet radiation of different intensity of irradiation. The layers which are applied onto the conductor wire in superposing manner have different properties wherein the wire is running through the apparatus after each occurring application of varnish.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims: 
     
       1. A method of producing electrical conductor wires, especially profiled heavy wires, having the steps of providing a vertical supporting frame supported on a platform and including at least two sets of guide pulleys arranged in longitudinal direction so that one set of guide pulleys is provided at a distance to the platform on one end of the supporting frame, and the other set of guide pulleys is provided on the top of the supporting frame; applying varnish onto the conductor wire in applying means above the one set of guide pulleys in separated tanks each provided with throughopenings for the wire to be coated; calibrating the thickness of the varnished layer by stripping off superfluous varnish in calibrating means directly above the applying means and each being associated with one individual tank; hardening the applied and calibrated varnish in a hardening chamber arranged between the other set of guide pulleys and the calibrating means, wherein the improvement comprises: applying the varnish onto the conductor wire in the tanks in groups or of laterally disposed individual tanks; hardening the applied and calibrated varnish by ultraviolet radiation by at least a first pair of ultraviolet radiators within the hardening chamber and disposed transversely to the guide motion of the wires, and at least a second pair of ultraviolet radiators located parallel above the first pair of ultraviolet radiators and having a higher intensity of radiation than the first pair of ultraviolet radiators; intensifying and reflecting the radiation by a first group of reflectors each provided behind each ultraviolet radiator and a second group of reflectors each arranged equi-distantly between two wires, the reflectors being perpendicular to the longitudinal axis of the respective ultraviolet radiator; and cooling by cooling means connected to the hardening chamber to achieve an optimum temperature. 
     
     
       2. A method as defined in claim 1, wherein the applying step includes applying a first layer of a well adhering varnish of high flexibility directly onto the surface of the wire, at least a second layer of a dielectrically high quality insulating varnish and surrounding the first layer, at least a third layer of an insulating varnish which is heat-resistant in the final state and superposing the second layer, and a fourth layer of an insulating varnish applied on the third layer and being mechanically resistant, especially resistant against abrasion and mar-resistant as well as suitably flexible in the final state, and the hardening step including hardening each layer by UV radiation after each respective application. 
     
     
       3. A method as defined in claim 2, wherein the hardening step includes preheating each varnished layer by subjecting to infra-red radiation and subsequently irradiating each varnished layer by sequential exposure to at least two sources of ultraviolet radiation having differing intensity of irradiation from each other. 
     
     
       4. A method as defined in claim 3, wherein each varnished layer is applied at a thickness of at least 5μ. 
     
     
       5. A method as defined in claim 4, wherein each varnished layer is applied at a thickness of 15 to 20μ. 
     
     
       6. A method as defined in claim 2, wherein the conductor wire to be coated is exposed to the ultraviolet radiation after each application of varnish for a period of less than 25 seconds. 
     
     
       7. A method as defined in claim 6, wherein the conductor wire to be coated is exposed to the ultraviolet radiation after each application of varnish for a period between 3 and 15 seconds. 
     
     
       8. A method as defined in claim 7, wherein the conductor wire to be coated is exposed to the ultraviolet radiation after each application of varnish at a temperature of more than 100° C. 
     
     
       9. A method as defined in claim 8, wherein the conductor wire to be coated is exposed to the ultraviolet radiation after each application of varnish at a temperature between 150° and 180° C. 
     
     
       10. A method as defined in claim 3, wherein each varnished layer is pretreated by short exposure to ultraviolet radiation and cured by at least a further ultraviolet radiation of higher intensity of irradiation. 
     
     
       11. A method as defined in claim 2, wherein the conductor wire having prehardened or partly hardened varnished layer is deflected twice after being cooled to below 100° C. for returning the wire for another passage in the same guide motion through the ultraviolet radiation, or after hardening of the respective layer to the following varnish to be applied. 
     
     
       12. A method as defined in claim 10, wherein at least one of the varnished layers is applied and/or hardened under exclusion of air or under protective gas. 
     
     
       13. An apparatus for producing electrical conductor wires, especially profiled heavy wires, having a vertical supporting frame supported on a platform, the supporting frame including at least two sets of guide pulleys arranged in longitudinal direction, one set of guide pulleys being provided at a distance to the platform on one end of the supporting frame, the other set of guide pulleys being provided on the top of the supporting frame; means for applying varnish onto the conductor wire, the applying means being located above the one set of guide pulleys and having separated tanks each provided with through openings for the wire to be coated, means for calibrating the thickness of the varnished layer by stripping off superfluous varnish, the calibrating means being arranged directly above the applying means and each being associated with one individual tank, a hardening chamber arranged between the other set of guide pulleys and the calibrating means, wherein the improvement comprises: an arrangement of the tanks in groups or of laterally disposed individual tanks, at least a first pair of ultraviolet radiators within the hardening chamber and disposed transversely to the guide motion of the wires, at least a second pair of ultraviolet radiators located parallel above the first pair of ultraviolet radiators and having a higher intensity of radiation than the first pair of ultraviolet radiators, a first group of reflectors each provided behind each ultraviolet radiator for intensifying and reflecting the radiation, a second group of reflectors each arranged equi-distantly between two wires, the reflectors being perpendicular to the longitudinal axis of the respective ultraviolet radiator, and cooling means connected to the hardening chamber to achieve an optimum temperature. 
     
     
       14. An apparatus as defined in claim 13, wherein the first pair of ultraviolet radiators are low pressure radiators arranged ahead of the second pair of ultraviolet radiators which are high pressure radiators wherein the low pressure radiators emit additionally infrared radiation for accelerating the heating of the varnish up to the reaction temperature. 
     
     
       15. An apparatus as defined in claim 13, wherein each reflector of the first group of reflectors has a concave shape, and each reflector of the second group of reflectors has a plane surface. 
     
     
       16. An apparatus as defined in claim 13, wherein the apparatus further comprises a shield located between the hardening chamber and the calibrating means, and a light trap between the other set of guide pulleys on the top of the supporting frame and the hardening chamber. 
     
     
       17. An apparatus as defined in claim 14, wherein an infrared radiator is arranged ahead of the pair of low pressure radiators. 
     
     
       18. An apparatus as defined in claim 13, wherein the cooling means including gas ducts at a distance from each other at each end wall of the hardening chamber, each of which end walls hving a passage in elongating direction of each ultraviolet radiator; and a group of baffle plates for cooling gas, each baffle plate is integrally developed with each side wall of the hardening chamber and is arranged inwardly and rectangularly thereof in axial parallel alignment with the ultraviolet radiators and located inbetween two superposing ultraviolet radiators. 
     
     
       19. An apparatus as defined in claim 18 wherein the gas ducts and passages on one of the two end walls are connected to the atmosphere, and the gas ducts and passages of the other of the two end walls are connected to at least one exhauster via a pipe system in which at least one flow volume regulator is provided for controlling the quantity of flow of cooling air depending on the temperature. 
     
     
       20. An apparatus as defined in claim 13, wherein the individual tanks of the applying means are trough-shaped and constructed with an inwardly inclined or curved side wall which is backwardly directed in which upper portion vertical slits open to the outside are provided as through openings wherein collecting containers are arranged below the backwardly directing bottom edge of the tanks for collecting the varnish flowing out of the slits, the collecting containers being connected with devices for continuously returning the varnish into the tank and arranged in a position which is rearwardly staggered at a small distance to the vertical guide motion of the wire passing the slits. 
     
     
       21. An apparatus as defined in claim 13, wherein each calibrating means has portions movable laterally from and towards each other in a guide which portions are kept together by elastic force and have a profile which corresponds to the wire to be coated.